In general, in a 3G (third generation) network provided as a public mobile communication network that establishes call connections among cellular phones or other UEs, a subscriber ID (IMSI: international mobile subscriber identity) for identifying a subscriber and a terminal ID (IMEI: international mobile equipment identifier) for identifying a radio terminal are set.
The IMEI is a unique value including information for identifying the UE, such as a serial number, as shown in FIG. 1.
The IMSI is stored in a subscriber identity module, such as a USIM (universal subscriber identity module) card, and the UE is activated by putting the subscriber identity module to the UE.
A system for the existing 3G network checks the IMEI by a MSC (mobile switching center) transmitting the IMEI acquired from the UE to an equipment identify register (EIR: equipment identify register) (see Patent Literature 1, for example).
The IMEI check is intended to check for an IMEI of a radio terminal used in an unauthorized manner, such as an IMEI of a radio terminal stolen and used in an unauthorized manner with a legitimate IMSI, thereby preventing unauthorized use of the radio terminal.
Besides, the possibility of a femto cell that establishes a connection to a mobile communication core network via a wired line installed in a household or office is attracting increasing attention in recent years.
The femto cell is configured so that a femto cell base station (femto AP) that achieves a small coverage of several tents of meters in radius establishes a radio connection among UEs. Typically, the femto cell achieves an indoor coverage, such as a coverage in a household or office. Therefore, a necessary coverage can be achieved without an extra cost of infrastructure construction of the existing macro cell base station (see Patent Literature 2, for example).